Conventionally, according to a railcar, such as the shinkansen (trademark), which travels at high speed, in order to obtain excellent comfortability in the railcar, a side sliding door that opens or closes a side entrance adopts an airtight structure to suppress pressure variation inside the railcar. For example, as shown in FIG. 5, PTL 1 discloses a railcar 100 configured such that both end portions of a side sliding door 120 are respectively pressed, via rubber seals 150, against a door pocket post 130 and a door stop post 140 respectively provided at both sides of a side entrance 110.
To secure the airtightness, the door pocket post 130 has to have relatively high stiffness. The door pocket post 130 has a double skin structure that is flat in a car-longitudinal direction. Specifically, the door pocket post 130 is configured such that an outer portion 131 and an inner portion 132 are coupled to each other by coupling portions 133. According to the railcar 100 disclosed in PTL 1, an edge portion 135, extending along the side entrance 110, of the door pocket post 130 is located outwardly of the inner portion 132 in a car-width direction, and a rubber seal 150 is attached to the edge portion 135.